Device and method for producing knitted fabric

ABSTRACT

A device and a corresponding method produce a knitted fabric with a knitting machine and a roving drawing and strengthening unit. The device has a roving supply unit with a roving, a stretching unit linked to the roving supply unit, and a spinning nozzle device provided downstream from the stretching unit in a roving conveying direction of the device forming a fiber strengthening segment by applying compressed air. An end thread gripping roller pair rotatable in opposite directions is provided downstream from the spinning nozzle device in the roving conveying direction delimiting the fiber strengthening segment. The device has a blow-off device for blowing off the spinning nozzle device and/or the stretching unit and a suction device for suctioning off loose fibers from the spinning nozzle device and/or the stretching unit. The suction device and the blow-off device are interconnected in a blow-off and suction system.

The present invention relates to a device for producing knitted fabric with a knitting machine and a roving drawing and strengthening unit, which comprises a roving supply unit with at least one roving, a stretching unit linked to the roving supply unit, a spinning nozzle device provided downstream from the stretching unit in a roving conveying direction of the device forming a fiber strengthening segment by applying compressed air and an end thread gripping roller pair rotatable in opposite directions provided downstream from the spinning nozzle device in the roving conveying direction delimiting the fiber strengthening segment, wherein the device comprises at least one blow-off device for blowing off the spinning nozzle device and/or the stretching unit and at least one suction device for sucking off loose fibers from the spinning nozzle device and/or the stretching unit. The invention further relates to a method for producing knitted fabric, wherein at least one roving is supplied to a stretching unit by means of a roving supply unit, compressed air being applied to a drawn roving exiting the stretching unit by a spinning nozzle device in a fiber strengthening segment, said roving being thus strengthened, wherein the fiber strengthening segment is delimited by an end thread gripping roller pair rotating in opposite directions through which the drawn, strengthened roving is lead in clamped fashion and an end thread exiting the end thread gripping roller pair is supplied to a knitting machine, wherein the spinning nozzle device and/or the stretching unit are blown off with at least one blow-off device and suction air is being sucked off with at least one suction device on the spinning nozzle device and/or the stretching unit.

The document WO 2009/043187 A1 discloses a device and a method for producing knitted fabric, in which a fiber assembly is directly supplied to the knitting needles of a knitting machine as well. The fiber assembly is drawn to a desired fineness in a stretching unit and is subsequently moderately strengthened by means of a pneumatically operating spinning nozzle. The fiber assembly is permanently strengthened by means of the spinning nozzle, wherein a core of the fiber assembly is entwined by overlapping and interlocked entwining fibers. After that, the transport-stable fiber assembly is transported to the knitting needles via a guiding tube. In order to support the transport of the fiber assembly through the guiding tube, the air escaping the outlet of the spinning nozzle, is induced into the guiding tube.

The production of knitted fabrics by means of a so-called false strand instead of a classic yarn has the advantage that knitted fabrics, which are particularly cost-effective and soft to the touch, can be produced.

However, problematic when producing and using such strengthened fiber assemblies such as in the document WO 2009/043187 A1 is, that due to the drawing twisting or transporting of the fiber assembly, smallest fiber particles, so-called lint, detach themselves from the fiber assembly, which can lead to the contamination of the device and the production environment and thus to a process interruption or to health hazards for people.

It is, however, not taken into account in the document WO 2009/043187 A1 that fiber lint forms during the production and the transport of the strengthened fiber assembly, which can negatively influence the process sequence and thus the process result. With the document WO 2009/043187 A1, there is a special risk that the air escaping the spinning nozzle, carrying loose fiber remains, causes blockages in the guiding tube.

For preventing fiber fly it is known from the prior art to use suction devices and blowing air devices for removing free fibers, especially from the stretching units and the spinning nozzle devices. Thus, the document WO 2007/093166 A2 discloses a suction/blowing air device for removing free fibers from a stretching unit. The suction/blowing air device comprises two blowing nozzles, which are provided on both sides of outlet nozzles of the stretching unit. Blowing air is induced in the blowing nozzles, whereby the rollers of the stretching unit can be kept clean from the lint as far as possible. The escaping blowing air is diverted over filling pieces that are arranged on the back side of the rollers of the stretching unit and is supplied to a central suction by means of air channels that are formed on the lower and upper surface of a housing covering the stretching unit and in which a slight underpressure prevails.

From the document DE 10 2011 053 396 B3 a device and a method of the type mentioned at the beginning are known, with which knitted fabric can be instantaneously produced from the drawn, strengthened roving, wherein the intermediate stages of the classical yarn production, such as yarn forming, spooling and, if necessary, rewinding of the yarn, are omitted. In order to achieve this, the document DE 2011 053 396 B3 suggests to draw a roving in a stretching unit coming from a roving supply unit, hereafter to apply compressed air in a spinning nozzle device and thus to strengthen it, subsequently to lead it through an end thread gripping roller pair, wherein the end thread gripping roller pair delimits the fiber strengthening segment of the spinning nozzle device and to supply the drawn, strengthened roving directly after that to a knitting point of a knitting machine. The roving is drawn to a desired fineness in the stretching unit and is twisted to a false strand by means of the spinning nozzles of the spinning nozzle device, wherein a core of the fiber assembly, in which the fibers that are primarily without twisting and mostly aligned parallel to each other, are entwined by entwining fibers. The end thread gripping roller pair arranged successively to the spinning nozzle device, clamps the roving strengthened by the spinning nozzle device and thus ends the formation of the false strand on the clamping point, whereby an immediate twisting of the entwining fibers strengthening the core of the drawn roving is prevented and the drawn, strengthened roving can be transported to the knitting needles of the knitting machine over relatively large distances.

On the device known from the document DE 10 2011 053 396 B3, a suction device for sucking off loose fibers is provided. The suction units of the used suction device are provided downstream from the spinning nozzle device, between the spinning nozzles of the spinning nozzle device and are provided on an outlet gripping roller pair of the stretching unit and are united to a suction channel formed in conic fashion. The fiber lint is centrally diverted by means of the suction channel, wherein, due to its conic form, even flow conditions are ensured over the system width.

A rotating ventilation device, provided above the device serves for the general clean-keeping of the device of the document DE 10 2011 053 396 B3, with which an even distribution of the fiber lint that has not been sucked off is carried out. Furthermore, blowing devices are used, with which the fiber lint is blown-off in the front and rear part of the stretching unit and thus a formation of fiber lumps is prevented. The used ventilation device, however, has the disadvantage that the air swirls generated by it, influence the amount of fiber at the exit of the stretching unit and thus fluctuations in the fineness of the yarn can be caused. Due to the ventilation device and the additionally used blowing device, unwanted accumulations of fiber lint and an associated disruption of the yarn formation can ensue. By using corresponding covering devices on certain spots of the device, this is being counteracted in the document DE 10 2011 053 396 B3. This, in turn, however, has the disadvantage that no fiber lint can be removed in the process on the spots covered with the covering devices so that here a contamination of the device can happen for whose removal the device needs to be stopped.

It is therefore the object of the present invention to provide a device and a method for producing knitted fabric with a knitting machine and a roving drawing and strengthening unit, in which all device components essential for the roving drawing and the roving strengthening can be kept clean effectively and cost-efficiently, in order to be able to increase the reliability of the device.

This object is, on the one hand, solved by means of a device of the above-mentioned type, in which the suction device and the blow-off device are interconnected in a blow-off and suction system, wherein the suction device comprises a suction air cleaning device with at least one ventilation device, and at least one exhaust air exit of the suction air cleaning device is connected to at least one air channel passing along over the at least one end thread gripping roller pair, which comprises at least one channel opening, which is aligned on or along the spinning nozzle device and/or on or along the stretching unit.

With the present invention, the used suction device is thus connected to a suction air cleaning device, whose cleaned exhaust air is usable as blow-off air for blowing off the spinning nozzle device and/or the stretching unit. With the present invention, this is possible due to the ventilation device provided on the suction air cleaning device, through which, on the one hand, the underpressure necessary for sucking off in one direction and, on the other hand, the excess pressure necessary for blowing off in the opposite direction, are provided. Thus, the device according to the invention comprises a self-contained blow-off and suction system, composed of relatively few system components which enables a targeted and effective blowing off of loose fibers and/or other loose particles of the spinning nozzle device and/or the stretching unit, a simultaneous, reliable sucking off of the blown-off loose fibers by means of the suction device and furthermore, the cleaning and reuse of the sucked air. Since the course-setting of the blow-off air and the suction air is realized by means of only one ventilation device with the present invention, the blow-off and suction system of the device according to the invention is realizable easy to construct and space-saving, and can be operated cost-effectively.

According to the invention, the suction air cleaning device thus comprises at least one ventilation device by whose effect exhaust air contaminated with loose fibers and/or other loose particles can be sucked in by certain components of the device and cleaned air is supplied again as blow-off air to the production process.

With the present invention, a ventilation device means a continuous-flow machine with at least one rotating running wheel, through which the air is conveyed and compressed and which comprises a suck-in side with underpressure and a pressure side with excess pressure in the operation. As a ventilation device, for example a fan runner, a ventilator or a blower can be used. An air current is generated by means of the rotation movement of the at least one running wheel of the ventilation device, which flows through the exhaust air outlet of the suction air cleaning device into the air channel towards the at least one channel opening.

The air current leaving the at least one channel opening is supplied to the production process for blowing off loose fibers and other particles of the spinning nozzle device and/or the stretching unit. While the air current of cleaned air generated by the ventilation device on the one hand flows towards the channel opening, on the other hand an underpressure exists on the side of the suction air cleaning device opposite the air channel. The underpressure generates an undertow which draws the air contaminated with loose fibers and/or other loose particles through at least one exhaust air inlet of the suction air cleaning device towards the ventilation device. Accordingly, by means of the rotation movement of the ventilation device, contaminated air is sucked into the suction air cleaning device while cleaned air is simultaneously given off from the suction air cleaning device.

With the device according to the invention, the ventilation device can be formed as axial, diagonal, radial, centrifugal, or tangential ventilator. The ventilation device is preferably provided within a housing of the suction air cleaning device. The running wheel of the ventilation device can comprise any number of blades whose form and size can be chosen application-specific. The running wheel of the ventilation device is driven by means of a drive motor, which can be directly integrated inside the suction air cleaning device or is provided outside the suction air cleaning device. The ventilation device is designed in such a way and/or is driven with such a power that the roving is damaged neither by the blowing-off process nor the suction process.

The air channel aligned on or along the spinning nozzle device and/or on or along the stretching unit, provided above the end thread gripping roller pair is supplied with blow-off air under excess pressure coming from the ventilation device. The blow-off air flows from the at least one channel opening onto the spinning nozzle device and/or the stretching unit, whereby existent loose fibers or other loose particles are blown-off in a downwards direction.

In general, the air channel can comprise one channel opening or several channel openings. The arrangement, formation, size and alignment of the at least one channel opening can hereby be chosen application-specific. Insofar the air channel comprises several channel openings, they can be provided evenly spaced apart from each other or concentrated in at least one area of the air channel, such as the holes of a shower head.

However, especially preferably the air channel comprises only one, continuous channel opening running along the spinning nozzle device and/or along the stretching unit, whereby the blow-off air can flow onto the spinning nozzle device and/or the stretching unit unhindered and thus loose fibers and other loose particles can be ideally removed from the spinning nozzles and/or the stretching unit rollers or from between the gaps between the spinning nozzles and/or between the stretching unit rollers.

After that, the blown-off loose fibers and/or other loose particles are sucked off by the suction device, whereby especially the area of the spinning nozzle device and/or the area of the stretching unit are cleaned. Hereby at least one suction opening of the suction device is preferably directly aligned towards the spinning nozzle device and/or the stretching unit. The alignment of the suction device towards the spinning nozzle device and/or the stretching unit has the advantage that the loose fibers can be directly sucked off on the position at which they predominantly occur, namely during the drawing of the roving in the stretching unit and the twisting of the roving by the spinning nozzle device. By sucking off the loose fibers and other loose particles at the same time, in particular a spreading of the loose fibers can be prevented, whereby a clean production environment can be guaranteed and process interruptions due to contaminations as well as endangerments of people due to loose fibers and other particles can be prevented.

With the present invention there is no limit with regard to the used suction device. Thus the suction device can for example comprise suction air channels or suction tubes aligned towards the spinning nozzle device and/or the stretching unit rollers, which can be lead directly to the areas in which a particularly large amount of fiber lint would be deposited. Such suction air channels can be formed both as fixed pipes as well as flexible hoses, whose length and thickness should preferably be chosen in such a way that the actual roving production process can proceed without interruptions and the material consumption for the suction lines is kept at a minimum. It is also advantageous, if the device according to the invention comprises several individual suction air channels that are united to a shared suction air channel, which are aligned to various areas of the spinning nozzle device and/or the stretching unit.

The suction air channels of the suction device are linked to at least one exhaust air inlet of the suction air cleaning device so that the loose fibers contained in the exhaust air can be filtered out of the exhaust air. The exhaust air cleaned in the suction air cleaning device is lead out of the suction air cleaning device by means of the at least one exhaust air outlet, is put under excess pressure by means of the ventilation device, flows into the air channel and is lead out of it as blow-off air.

It has proven to be particularly advantageous, if the at least one channel opening of the air channel is aligned in such a way that it is not only aligned on or along the spinning nozzle device and/or on or along the stretching unit, but at the same time towards the at least one suction opening of the suction device.

The air channel can be formed as a fixed or flexible pipe or pipe system. The air channel preferably runs horizontally, that is parallel to the stretching unit rollers. The air channel can be installed at a fixed position on the device according to the invention but can also be variable in its height position, for example in order to form the intensity of the exhaust air variable and/or to make maintenance work on the device easier. Especially when forming the air channel as a pipe system, the air channel can be formed in such a way that several junctions, if necessary with different alignments, exit a main flow channel which in turn can be composed of individual pipes or can be formed of a single pipe, which enable it to blow off different areas of the device.

It has proven to be particularly preferable, if a lint filter, comprising a perforated drum with at least one lint filter layer provided around the perforated drum, is provided on the underpressure side of the ventilation device.

In this embodiment of the invention, the sucked in exhaust air contaminated by the fiber lint is lead from the exhaust air through the lint filter device in order to remove the loose fibers and other parts. The lint filter device comprises a perforated drum, that is, a cylindrical drum that is hollow on the inside, with holes provided in the drum circumference, that is, the cylinder jacket. Due to the holes of the perforated drum, underpressure prevails around the perforated drum, which is coupled with the underpressure side of the ventilation device with its drum bottom. Thereby, the contaminated exhaust air is initially sucked against the drum circumference. At least one lint filter layer is provided around the drum circumference, that is, the cylinder jacket. The lint filter layer forms a lint filter for the contaminated exhaust air. The lint filter layer is more closely-meshed than the perforation structure of the perforated drum, that is, it has openings with a smaller diameter than the diameter of the holes in the perforated drum so that lints remain on the lint filter layer and are not sucked inside the perforated drum. The lint filter layer can for example be formed of a filter wire mesh.

The lint filter layer is preferably interchangeable. Thus it is possible, especially when forming the lint filter device as a perforated drum, to replace the used lint filter device with a lint filter device comprising other characteristics, for example with openings with different diameters and/or a different number of openings. This has proven to be particularly advantageous with regard to the production and usage of different yarns with different characteristics. An exchange of the perforated drum is furthermore also advantageous in case of a damage of the perforated drum or for cleaning the perforated drum.

In particularly favourable embodiment of the present invention, a hole-free panel in an area of the inner circumference of the perforated drum and a wiping device opposite the panel, outside on the perforated drum, are provided. Due to the hole-free panel, no underpressure prevails on the area of the outer circumference of the perforated drum, which is situated opposite the panel. Thus, no contaminated exhaust air is being sucked in here. Thereby, a wiper of the wiping device can easily be led up to the lint filter layer lying on the outer circumference of the perforated drum, in order to wipe off the lint from it. For this, the wiper preferably extends across the entire length of the perforated drum.

In optional embodiments of the device according to the invention, other devices for cleaning the lint filter device can be provided inside the suction air cleaning device, so that the lint filter layer for example does not need to be removed from the suction air cleaning device for its cleaning. Instead of the wiping device described above, a suction device or rinsing device can also be used as linter filter cleaning device. The respectively used lint fiber cleaning device can be connected to a central dirt absorption device.

The lint filter device is particularly preferably linked or linkable to/with a monitoring device which provides information concerning the contamination or air permeability of the lint filter device for a user of the device according to the invention. By means of the monitoring device can thus for example be displayed, whether the lint filter device is blocked and/or needs to be cleaned. Furthermore, a defect of the lint filter device or the like can also be displayed by means of the monitoring device.

In another appropriate embodiment of the device according to the invention, a gear ring is provided around the inner circumference of the perforated drum for adjusting the position of the perforated drum in relation to the wiping device. An adjustment part can be inserted into the gear ring, whereby the perforated drum can be moved further by a rotation angle. Corresponding to the rotation angle, the wiping device thereby scrapes off a part of the fiber fleece deposited on the lint filter device during the process.

In an advantageous embodiment of the present invention, the device comprises an auxiliary thread supply through which at least one auxiliary thread can be supplied to the stretching unit, whereby the at least one air channel runs along at least partially also over the auxiliary thread supply and comprises at least one channel opening, which is aligned on or along the auxiliary thread supply.

By using an auxiliary thread, the strength of the drawn, strengthened roving supplied to the knitting machine and the reliability of the process carried out on the device according to the invention can be increased. If an auxiliary thread is supplied to the roving treated in the device according to the invention, a core-coat-yarn is formed, wherein the core is formed by the auxiliary thread. The used auxiliary thread can be an inelastic or an elastic thread. The auxiliary thread supply preferably comprises a withdrawal realized by an outlet roller pair of the stretching unit, whereby the auxiliary thread can be taken up by the outlet roller pair of the stretching unit and can be bound into the drawn roving. The auxiliary thread can for example also be transported to the stretching unit with the aid of auxiliary thread gripping rollers provided inside the auxiliary thread supply.

In order to protect the auxiliary thread supply or at least individual components of the auxiliary thread supply, such as the auxiliary thread gripping rollers, from loose fibers or other loose particles and thus to ensure a permanently reliable functionality of the auxiliary thread supply, it has proven to be advantageous to form the air channel in such a way that at least a part of the cleaned air flowing out of the air channel can encounter the auxiliary thread supply. For this purpose, at least one channel opening provided in the air channel is aligned with the auxiliary thread supply. However, several channel openings can also be aligned with the auxiliary thread supply. Also, a junction, which is directly aligned with the auxiliary thread supply and comprises at least one channel opening, can depart from the air channel.

Insofar the air channel as well as the suction air channel comprise several openings and/or junctions, through which the air can flow, an air duct system can be provided with the device according to the invention in the air channel and/or the suction air channel, which closes or opens individual openings and/or junctions of the air channel and/or the suction air channel on request and thus enables a targeted air flow as required.

In a favourable advanced embodiment of the device according to the invention, the suction air cleaning device is a collective suction air cleaning device to which all suction devices provided on the device lead.

By merging the, due to the individual suction devices, contaminated air in a single suction air cleaning device, the exhaust air of the device can be centrally processed and can be forwarded to the desired operation sites as blow-off air. By centrally processing the air, the costs for the device according to the invention as well as the expenses for maintenance and repair can be kept low.

Especially when using a central suction air cleaning device, it is useful to use an air duct system as described before.

In order to ensure even flow conditions across the system width of the device according to the invention, a suction air collection channel extending parallel to the air channel, extending over its entire length, is preferably provided between the suction air cleaning device and at least one suction channel of the suction device.

The object of the present invention is furthermore solved by a method of the above-mentioned type, in which the suction air is lead to a suction air cleaning device, in which on the one hand an underpressure is generated by means of at least one ventilation device, through which loose fibers are removed from the suction air, and on the other hand, the cleaned exhaust air gained from the suction air is put under excess pressure, is led, coming from the suction air cleaning device, in at least one air channel running along above the at least one end thread gripping roller pair and through at least one channel opening of the air channel by forming at least one air curtain aligned on or along the spinning nozzle device and/or on or along the stretching unit.

With the method according to the invention, loose fibers, which are detached from the treated roving due to the process of yarn production, especially by means of a rotation generation of air jets in the spinning nozzle device, are sucked off from the device on which the method according to the invention is being carried out and/or from the environment of this device by means of the suction device. Preferably, the loose fibers as well as other particles are sucked off from the stretching unit drawing the roving and/or from the spinning nozzle device twisting and strengthening the roving. By sucking off the loose fibers and/or other loose particles, a spreading of these and thus a contamination of the production environment can be prevented, whereby the process stability can be increased.

For sucking off the air contaminated with the loose fibers and/or other loose particles, the suction air cleaning device, to which the suction air is forwarded, comprises at least one ventilation device, which sucks off the contaminated air from the device respectively the environment of the device on which the method according to the invention is being carried out, by generating an underpressure.

The air, which is cleaned of fibers and other particles in the suction air cleaning device, is led in an air channel exiting the suction air cleaning device, running along the end thread gripping roller pair by means of an excess pressure generated by the ventilation device.

The ventilation device comprises a rotatable running wheel for conveying the air. As a result of a rotating movement of the running wheel, the air is conveyed, whereby at the same time a compression of the air for building up a pressure ratio between the suction side respectively underpressure side, that is the side of the ventilation device onto which the contaminated air is sucked by the ventilation device and a blowing side respectively excess pressure side of the ventilation device, that is the side of the ventilation device, to which the cleaned air is supplied, ensues.

The cleaned exhaust air flowing through the air channel exits through at least one channel opening formed in the air channel and is led on or along the spinning nozzle device and/or on or along the stretching unit by forming an air curtain. The air curtain is particularly effective if only one, continuous channel opening is formed in the air channel so that the air curtain encounters the spinning nozzle device and/or the stretching unit like a continuous air blanket.

By means of the air flowing on or along the spinning nozzle device and/or on or along the stretching unit, loose fibers and other particles can be ideally blown off from the device and the treated roving and the device and the roving can thus be easily cleaned of lint which would possibly impede the processing of the roving. Hereby it has proven to be particularly advantageous if the air channel respectively the at least one channel opening is aligned in such a way that the emitting air can be ideally sucked off by the suction air cleaning device after the blowing-off of the spinning nozzle device, the stretching unit and/or the yarn and thus the receiving of fibers and other particles.

In a particularly appropriate embodiment of the method according to the invention, the suction air is led through a lint filter device linked to the underpressure side of the at least one ventilation device, which comprises a perforated drum with at least one lint filter layer provided around the perforated drum, whereby loose fibers contained in the suction air are collected by the lint filter device. The sucked in air is freed from loose fibers and/or other loose particles when flowing through the lint filter device. The cleaned air exiting the lint filter device flows inside the perforated drum and is, supported by the excess pressure built up by means of the ventilation device, forwarded to the at least one air channel.

In a special embodiment of the method according to the invention, the lint filter device can be cleaned by means of a lint filter device, wherein the lint filter device can be freed of the collected fibers and/or other collected particles by means of suction, rinsing, blowing-off or wiping. The fibers and/or particles sucked off, blown off, rinsed off or wiped off by the lint filter device can be for example forwarded to a central dirt holding device.

The wiping-off of a lint layer on the lint filter device is particularly effective if a hole-free panel is provided in an inner circumference of the perforated drum, a wiping device is provided on the outside of the perforated drum opposite the panel and a gear ring is provided around the inner circumference of the perforated drum, wherein the position of the perforated drum is adjusted in relation to the wiping device by means of the gear ring in temporal intervals.

Furthermore, it has proven to be advantageous if the lint filter device is controlled by means of a monitoring device, wherein it can for example be displayed whether the lint filter device is blocked, needs to be cleaned or a defect exists on the lint filter device by means of the monitoring device.

In a particularly preferred embodiment of the method according to the invention, the at least one air channel also runs along the at least one auxiliary thread supply and by means of the at least one channel opening of the air channel, at least one air curtain is aligned on or along the auxiliary thread supply.

By binding an auxiliary thread respectively a so-called core thread into the roving, the stability of the roving can be increased and thus the reliability of the knitting process can be enhanced. For this purpose, the auxiliary thread is supplied to the roving in the stretching unit in a preferred embodiment of the method according to the invention. Thereby, it is particularly practical if the auxiliary thread is pulled off by means of an outlet roller pair of the stretching unit, whereby the auxiliary thread can be easily included between the fibers of the roving drawn by the stretching unit. However, in other optional embodiments of the method according to the invention, the auxiliary thread furthermore can be supplied to the roving elsewhere. For gently transporting the auxiliary thread to the roving, the auxiliary thread can also be conveyed by means of at least one auxiliary thread gripping roller pair enclosed by the auxiliary thread supply.

For ensuring an easy transport of the auxiliary thread to the roving as well as an uncomplicated binding of the auxiliary thread into the roving, the cleaned air flowing from the channel opening is applied to the auxiliary thread supply. By blowing off the auxiliary thread supply, fibers and other particles can be removed from the auxiliary thread supply and the auxiliary thread and thus the process safety of the method according to the invention can be increased.

According to another preferred embodiment of the method according to the invention, the suction air sucked off on the device is collectively led to the suction air cleaning device, whose cleaned exhaust air is led across all spinning nozzle devices arranged on the device.

Preferably, contaminated air is not only sucked off in the area of the stretching unit and/or the spinning nozzle device, but also in other areas of the device, whereby the cleanness of the production environment and thus the process safety can be further increased. In order to keep the costs as well as the expense for maintenance and repair as low as possible, it has proven to be particularly advantageous if the exhaust air is led to a shared, central suction air cleaning device, in which the contaminated exhaust air is freed of loose fibers and/or loose particles. The air cleaned in the suction air cleaning device can subsequently be forwarded to the spinning nozzle device and/or the stretching unit. The cleaned air can furthermore also be used for blowing off further components of the device, the auxiliary thread and/or the roving for removing fibers and/or particles from those.

Preferred embodiments of the present invention, including their structure, function and advantages are explained in more detail in the following using figures, wherein

FIG. 1 schematically shows details of an embodiment of a device according to the invention in a side view;

FIG. 2 schematically shows the details of the device from FIG. 1 in a frontal view;

FIG. 3 schematically shows an embodiment of a perforated drum usable on a device according to the invention in a perspective view; and

FIG. 4 schematically shows the perforated drum from FIG. 3 in a frontal view.

The figures schematically show details of an embodiment of the device according to the invention for producing knitted fabric. For the sake of clarity, a multitude of further machine details, which for example relate to the housing of the device, the media supply, the device control and so on are left out of the figures. Concerning such details, it is hereby fully referred to the explanations relating to the document DE 10 2011 053 396 B3, which describes the basic structure of the device according to the invention, wherein the device according to the invention comprises a blow-off and suction system 1 changed over the document DE 10 2011 053 396 B3, whose elements are primarily depicted in the subsequently described figures.

FIG. 1 shows a part of the device according to the invention in a side view, while FIG. 2 shows the part of the device according to the invention shown in FIG. 1 in a side view.

The device according to the invention comprises a knitting machine not depicted in the figures as well as a roving drawing and strengthening unit 10 supplying drawn, strengthened roving to the knitting machine. The roving drawing and strengthening unit 10 comprises a roving supply unit also not depicted in the figures, on which at least one roving is for example stocked on at least one supply spool.

The roving drawing and strengthening unit 10 furthermore comprises a stretching unit 5 for drawing the roving supplied to the stretching unit 5 by the roving supply unit. The roving not depicted in the figures traverses the stretching unit 5 in a roving conveying direction A, that is vertically from bottom to top in the depicted embodiment.

The stretching unit 5 used in the embodiment of the FIGS. 1 and 2 comprises three fixed, continuous lower rollers 511, 521, 531, which are faced by rolls 512, 522, 532 rotatable when operating the device and pressable against the lower rollers 511, 521, 531 by means of a lever arm 50 by forming corresponding roller pairs 51, 52, 53 indicated in FIG. 2. The rolls 512, 522, 532 can for example be rubber rolls.

The roving drawing and strengthening unit 10 furthermore comprises a spinning nozzle device 6 provided downstream from the stretching unit 5 in the roving conveying direction A. When operating the device, compressed air is being applied to a drawn roving exiting the stretching unit 5 in a fiber strengthening segment by means of the spinning nozzle device 6, said roving being thus strengthened. In the depicted embodiment, the spinning nozzle device 6 is comprised of two spinning nozzles 61, 62 automatically conveying the drawn roving in a roving conveying direction A.

The device according to the invention furthermore comprises a suction device 11. In the embodiment depicted in FIGS. 1 and 2, the suction device 11 comprises four suction channels 3 a, 3 b, 3 c, 3 d by means of whose loose fibers and/or loose particles can be sucked off on different spots of the roving drawing and strengthening unit 10.

A first suction channel 3 a is therein aligned towards the lower roller 531 of the outlet gripping roller pair 53 of the stretching unit 5. In the depicted embodiment, the suction channel 3 a is aligned with the lower roller 531 at approximately a right angle to the roving conveying direction A.

A second suction channel 3 b is aligned with an area between the spinning nozzles 61, 62 of the spinning nozzle device 6 in order to remove loose fibers and/or loose particles from the spinning nozzles 61, 62. The suction channel 3 b is aligned to the spinning nozzle device 6 at approximately a right angle to the roving conveying direction A.

A third suction channel 3 c is provided downstream from the spinning nozzle device 6 in a roving conveying direction A.

A fourth suction channel 3 d runs along over the spinning nozzle device 6, is bent over the spinning nozzle device 6 and is aligned at an angle from above with the outlet roller pair 53 of the stretching unit 5.

The suction channels 3 a, 3 b, 3 c, 3 d lead to a shared suction air channel 30 in which the suction air is conducted in the suction flow direction B and which leads to a suction air cleaning device 4 of the device. The suction air cleaning device 4 is enclosed by a housing 41, in which a lint filter device is provided. In the depicted embodiment, the lint filter device comprises a perforated drum 7, that is a cylindrical drum that is hollow on the inside, in whose cylinder jacket through holes are provided. A possible embodiment of the perforated drum 7 is depicted in a perspective view in FIG. 3 and in a frontal view in FIG. 4. The perforated drum 7 can for example be formed of steel.

A lint filter layer 70 is provided around the cylinder jacket of the perforated drum 7. The lint filter layer 70 comprises a multitude of passage openings, whose diameter is smaller than the diameter of the holes of the perforated drum 7. Thus, the fiber lint contained in the suction air is collected on the lint filter layer 70 and only the suction air cleaned from the fiber lint reaches the inside of the perforated drum 7. The lint filter layer 71 can for example be formed as a cylindrical, knotted or knit grid, whose loop widths are so small that the loose fibers and/or other loose particles that are generated during the roving processing on the device according to the invention, are prevented from permeating the grid to the inside of the perforated drum 7. The lint filter layer 71 can be for example formed of a filter wire mesh.

Furthermore, a panel 71 is arranged within the perforated drum 7. In the depicted embodiment, the panel 71 is on the bottom of the perforated drum 7. Outside on the perforated drum 7, opposite the panel 71, a wiping device 72 is provided on the cylinder jacket of the perforated drum 7.

For sucking off the air contaminated with loose fibers and/or loose particles on the roving drawing and strengthening unit 10, a ventilation device 8 is subsequently provided on an opening of a housing wall 411 of the housing 41. An underpressure side of the ventilation device 8 is thereby linked to the inside of the perforated drum 7, whose open drum bottom 73 leads to the opening of the housing wall 411 opposite the ventilation device 8. Accordingly, an underpressure is generated inside the perforated drum 7 and also inside the housing 41, resulting in a suction effect in the suction channels 30, 3 a, 3 b, 3 c, 3 d connected to the housing 41. The excess pressure side of the ventilation device 8 is situated outside the housing 41 so that an excess pressure arises outside the housing 41, wherein the pressure difference between the inside of the housing 41 and the area outside the housing results in an air flow towards the blow-off device 9, as shown by the arrow C.

In the embodiment depicted in the figures, the underpressure side of the ventilation device 8 closes flush around the open drum bottom 73 with the housing wall 411, however, it can also overtop it or to a certain extent can protrude inside the suction air cleaning device 4 respectively the perforated drum 7. However, the open drum bottom 73 can comprise a larger diameter than the underpressure side of the ventilation device 8.

Due to the rotational movement of at least one ventilation blade 81 of the ventilation device 8, an underpressure is generated, which causes the air to be sucked from the suction air channel 30 and thus from the suction channels 3 a, 3 b, 3 c, 3 d towards the ventilation device 8.

Due to the suction effect, the suction air sucked off from the roving drawing and strengthening unit 10 initially flows along the suction air channel 30 tapering in the suction flow direction B and reaches, coming from this suction air channel 30 via an exhaust air inlet 42, the suction air cleaning device 4. In order to be able to ensure a constant suction speed across the entire length of the suction air channel 30, the suction air channel 30 leads in a suction collection channel 43 inside the suction air cleaning device 4, which is formed conical in its length expansion running parallel to the length expansion of the air channel 9 and/or parallel to the length expansion of the rollers of the stretching unit 5.

The suction collection channel 43 is opened towards the inside of the housing 41. Within the suction air cleaning device 4, the sucked air moves towards the ventilation device 8 arranged on the housing wall 411, wherein the sucked air hereby flows through the cylinder jacket of the perforated drum 7 into the inside of the perforated drum 7. Thereby, the suction air passes the lint filter layer 70 provided around the perforated drum 7. When the contaminated air flows through the lint filter layer 70, the loose fibers and/or other particles contained in the sucked air are taken in by the lint filter layer 70 filtered from the exhaust air so that only exhaust air cleaned from fiber lint and particles flows inside the perforated drum 7 and thence to the ventilation device 8.

Due to the rotational movement of the ventilation blades 81, an excess pressure is generated outside the suction air cleaning device 4, which causes the cleaned air to flow from the inside of the perforated drum 7 through at least one exhaust air outlet of the suction air cleaning device 4 in the flowing direction C into the air channel 90. As depicted in FIG. 1, at least one channel opening 91 of the air channel 90, which is preferably a single, continuous channel opening running parallel to the rollers of the stretching unit 5, is thereby aligned with the spinning nozzle device 6 and/or the stretching unit 5 so that the cleaned exhaust air can be used for blowing off loose fibers and/or other particles of the stretching unit 5 and/or the spinning nozzle device 6. Afterwards, the blow-off-suction-circle of the present invention is completed by sucking away the loose fibers and/or particles blown off from the stretching unit 5 and/or the spinning nozzle device 6 by means of the suction channels 3 a, 3 b, 3 c, 3 d.

By processing the sucked air and using the cleaned air for blowing off the stretching unit 5 and/or the spinning nozzle device 6 in the present invention, an energetically cost-effective device and a corresponding method are provided, by means of which the stretching unit 5 and/or the spinning nozzle device 6 can be easily and efficiently freed of loose fibers and/or other particles.

To ensure a continuous air flow of cleaned air in the air channel 90 and thus out of the channel opening 91, a wiping device 72, for example in form of a wiper lip, is provided on the cylinder wall of the perforated drum 7, adjoining the lint filter layer 71 for wiping a lint fleece accumulating on the lint filter layer 72. The regular wiping of the loose fibers and/or other particles accumulated on the lint filter layer 71 prevents a blocking of the passage openings of the lint filter layer 71 formed as a grid and thus ensures a continuous air flow in the air channel 90.

As can be discerned from FIG. 1, the wiping device 72 touches the lint filter layer 71 at least during the cleaning process, in order to be able to wipe off the loose fibers and/or particles accumulated on the outer side of the lint filter layer 71. Since the fibers and/or particles are sucked tightly to the lint filter layer 71 due to the underpressure generated by the ventilation device 8 and thus their wiping by means of the wiping device 72 is hindered due to the underpressure, a hole-free panel 71 is arranged inside the perforated drum opposite the wiping device 72. Due to the panel 71, no underpressure forms on its opposing side of the perforated drum 7, whereby the loose fibers and/or particles accumulated in this area can be easily wiped off from the lint filter layer 71. A rotating movement of the perforated drum 7 with the lint filter layer 71 situated on it in relation to the wiping device is 72 helpful for wiping off the lint layer from the lint filter layer 71.

In order to enable an easy turning of the perforated drum 7 with the lint filter device 71, the perforated drum 7 comprises a gear ring in the area of the open drum bottom 73 in the embodiment depicted in FIG. 3. By an intervention of a slide formed corresponding to the gear ring 74 or another correcting actuator not depicted here into the gear ring 74, the perforated drum 7 alongside the lint filter layer 71 provided on it can be turned around the drum axis, that is the position of the perforated drum 7 can be changed in relation to the wiping device 72 for an eased wiping of the lint fleece from the lint filter layer 71.

In a simple embodiment of the suction air cleaning device 4, the panel 71 can just be placed in the perforated drum 7 and thus automatically lies in a lower area of the perforated drum 7 due to the gravity. The wiping device 72 is hereby provided below the perforated drum 7. In other embodiments of the present invention, however, the panel 71 can also be firmly fixed in the suction air cleaning device 4. Insofar the panel 71 is provided fixed in the suction air cleaning device 4, it can also be provided on any other position of the circumference of the perforated drum 7, the only important thing being that the wiping device 72 is arranged opposite the panel 71. 

1-12. (canceled)
 13. A device for producing knitted fabric, comprising: a knitting machine; a roving drawing and strengthening unit having a roving supply unit with at least one roving, a stretching unit coupled with said roving supply unit, a spinning nozzle device disposed downstream from said stretching unit in a roving conveying direction of the device forming a fiber strengthening segment by applying compressed air, and an end thread gripping roller pair rotatable in opposite directions and disposed downstream from said spinning nozzle device in the roving conveying direction and delimiting said fiber strengthening segment; at least one blow-off device for blowing off said spinning nozzle device and/or said stretching unit; at least one suction device for suctioning off loose fibers from said spinning nozzle device and/or said stretching unit; a blow-off and suction system, said suction device and said blow-off device are interconnected in said blow-off and suction system; at least one air channel running along over said end thread gripping roller pair; said suction device having a suction air cleaning device with at least one ventilation device, said suction air cleaning device having at least one exhaust air outlet connected to said at least one air channel; and said at least one air channel having at least one channel opening aligned on or along said spinning nozzle device and/or on or along said stretching unit.
 14. The device according to claim 13, further comprising a lint filter assembly having a perforated drum with at least one lint filter layer disposed around said perforated drum, said perforated drum disposed on an underpressure side of said ventilation device.
 15. The device according to claim 14, further comprising: a hole-free panel disposed in an inner circumference of said perforated drum; and a wiping device disposed on an outer side of said perforated drum opposite said hole-free panel.
 16. The device according to claim 15, further comprising a gear ring disposed around said inner circumference of said perforated drum for adjusting a position of said perforated drum in relation to said wiping device.
 17. The device according to claim 13, further comprising an auxiliary thread supply through which at least one auxiliary thread can be supplied to said stretching unit; and wherein said at least one air channel at least partially also runs along over said auxiliary thread supply and contains said at least one channel opening, which is aligned on or along said auxiliary thread supply.
 18. The device according to claim 1, wherein: said suction device has a plurality of suction channels; and said suction air cleaning device is a collective suction air cleaning device into which all said suction channels lead.
 19. The method according to claim 13, further comprising a suction collection channel formed in a conical fashion in its length expansion, extending parallel to said air channel and is disposed between said suction air cleaning device and at least one suction channel of said suction device.
 20. A method for producing a knitted fabric, which comprises the steps of: supplying at least one roving to a stretching unit by a roving supply unit; applying compressed air to a drawn roving exiting the stretching unit by a spinning nozzle device in a fiber strengthening segment, being thus strengthened, wherein the fiber strengthening segment is delimited by an end thread gripping roller pair rotating in opposite directions through which a drawn, strengthened roving is led in clamped fashion and an end thread exiting the end thread gripping roller pair is supplied to a knitting machine; blowing off the spinning nozzle device and/or the stretching unit via at least one blow-off device; suctioning off exhaust air by means of at least one suction device on the spinning nozzle device and/or the stretching unit; leading suction air to a suction air cleaning device, in the suction air cleaning device an underpressure is generated by means of at least one ventilation device, through the suction air cleaning device loose fibers are led out of the suction air; and putting cleaned exhaust air gained from the exhaust air under excess pressure, the cleaned exhaust air being under excess pressure is led, starting from the suction air cleaning device, in at least one air channel running along over the end thread gripping roller pair and through at least one channel opening of the air channel by forming at least one air curtain aligned to or along the spinning nozzle device and/or on or along the stretching unit.
 21. The method according to claim 20, which further comprises leading the suction air through at least one lint filter device connected to an underpressure side of the at least one ventilation device, the lint filter device having a perforated drum with at least one lint filter layer provided around the perforated drum, wherein loose fibers contained in the suction air are collected by the lint filter device.
 22. The method according to claim 21, which further comprises: providing a hole-free panel in an inner circumference of the perforated drum; providing a wiping device on an outer side of the perforated drum opposite the lint filter layer; and providing a gear ring on the inner circumference of the perforated drum, wherein a position of the perforated drum is adjusted in relation to the wiping device by means of the gear ring in temporal intervals.
 23. The method according to claim 20, wherein the at least one air channel also runs along over an auxiliary thread supply and at least one air curtain is aligned on or along the auxiliary thread supply by means of the at least one channel opening of the air channel.
 24. The method according to claim 20, which further comprises leading the suction air suctioned off on the device collectively to the suction air cleaning device, whose cleaned exhaust air is led over the spinning nozzle device. 